US law enforcement agencies using spy planes to gather phone data: Report

US law enforcement agencies are using spy planes equipped with military-grade snooping technology to gather information from millions of smartphones in the US, The New Zealand Herald reported.

According to The Wall Street Journal, Cessna airplanes equipped with "dirtboxes" were being used to mimic mobile phone towers, helping the US Marshals Service track criminals as they recorded innocent citizens' data.

The project got underway in 2007 and was operating from five metropolitan airports in the US. According to the WSJ report, the planes, between them had a flying range covering the majority of the US population. The report cited "sources familiar with the programme".

The US justice department neither confirmed nor denied the existence of the programme, though the technology being used was similar to a known method called "Stingray".

The Stingray devices and "dirtboxes" used readily available components to collect mobiles' International Mobile Subscriber Identity (IMSI), an identifying code unique to each device.

This could be used to track individuals' movements via their mobiles but worked indiscriminately, gathering information from a general area.

US agencies known to collect information include the FBI, Drug Enforcement Agency, Secret Service, Army, Navy and the Marshals.

According to security experts the capabilities had "become, for better or worse, globalised and democratised."

Security expert professor Paul Woodward told BBC, "in essence, one spoofed networks by  pretending to be a cell tower. One could turn off encryption and then extract all sorts of info such as calls made, where, when, etc."

He added it was easily done and doing it from the air was the obvious place to do it, but the question was under what legislation they were doing it and what they were doing with the data.